use DigitalCreative\InlineMorphTo\InlineMorphTo;

class Article extends Resource
{
    public function fields(Request $request)
    {
        return [
            ...
            InlineMorphTo::make('Template')->types([
                \App\Nova\Video::class,
                \App\Nova\Image::class,
                \App\Nova\Text::class,
                \App\Nova\Gallery::class,
            ]),
            ...
        ];

    }
}